Everything you ever wanted to know about CPRM, but ZDNet wouldn't tell you…

CPRM or Content Protection for Recordable Media is a mechanism for controlling the copying, moving and deletion of digital media on a host device, such as a personal computer, or other digital player. It's already used in specific removable media, and is now being proposed for inclusion in the ATA specification, for hard drives.

Each CPRM-compatible ATA hard drive is individually signed, and authenticates the playback and movement of files on the device against a central server using CPRM-compliant software.

2. Is CPRM going to go into hard drives? Has this already happened? If it hasn't, will it happen?

The NCTIS T.13 committee, which sets the ATA hard disk standard, will meet for the third time to debate a proposal to extend the ATA command set to include CPRM in February. The proposal is "optional": devices may include CPRM and be deemed "compliant" with the ATA specification, but not have CPRM available to client software.

3. How does this "break" existing software?

In itself, it doesn't. Several things must happen. The hardware must be CPRM-compliant, and have CPRM activated in the firmware by the manufacturer, and the user must then download CPRM-ready media, such as audio files or documents, using CPRM-compliant software. The media downloaded must also have restrictions placed upon its reproduction - but then, that's the whole point of protecting files with CPRM isn't it?

The user must also have the keys - or access to the keys - when the signed media is moved, or copied or deleted. Downloaded media is associated with an individual drive, so if you can't produce the keys, then restore operations will fail. If you can't produce the keys, then RAID software will break. If you can't produce the keys, file optimisation and disk defragmenters will be unable to move the blocks used by the media. If you can't produce the keys, one-to-many imaging programs will break...

4. So this means I'll be able to sign application binaries, or entire software distributions, to prevent unauthorised duplication?

Yes

5. So why is Microsoft against this, if it prevents wholesale "piracy" of its software in developing nations?

Um, can you ask us another...?

6. So I'll still be able to trade MP3s and burn my audio CDs, and I don't need to worry about it.

Yes, but for how long? You're assuming that in the future that content producers, such as the folk who produce your audio CDs, will ignore CPRM, that the default mass-market download mechanism (let's call it "Internet Explorer") will ignore CPRM, and that mass-market hardware vendors will not produce CPRM drives. That's a lot of assumptions, isn't it? And it doesn't it make you wonder why they went to the trouble of inventing it?

Follow the money.

7. Who is behind CPRM?

The intellectual property behind CPRM is owned by the 4C Entity, which comprises Intel, IBM, Matsushita and Toshiba. Patents are administered by License Management International, LLC. The former created the CSS copy-control technology, and the latter is involved in litigation against DeCCS authors.

8. OK, who is really behind CPRM?

You can work that one out yourselves. According to Intel, the entertainment distributors wanted to exclude the personal computer industry from playback of digital entertainment content, and the computer industry - keen to see the PC as a playback device for DVD and audio - was obliged to meet them half-way.

We certainly believe that Intel executives know that its continuing growth depends on it being an open platform: it has aided non-Microsoft OSes, and encouraged the adoption of Intel technology in non-PC platforms that conceivably threaten the PC itself, but grow the market for Intel-blessed, industry standard PC technology. Intel has also noticed that Napster has become a primary reason why people buy PCs, and in promoting the peer-to-peer architecture, implicitly promotes an architecture that encourages the free exchange of information and content. Intel tells us that CPRM on ATA threatens this growth. Nice Intel! So why don't they remove it (jump to 11 for technical details) ? And why does Intel continue to sponsor research projects such as HDCP? Nasty Intel!

It's possible that IBM and Intel have market power that they don't realise, or simply aren't willing to flex. For example, both companies have prepared for a future where mobile internet terminals ("smartphones") are the dominant consumer playback device. Both IBM and Intel have the market power to influence content standards in such a market for the good.

9. The 4C Entity says CPRM on ATA is optional. Surely no one will be stupid enough to build it into drives?

Think chicken-and-egg: the key here is "mass market".

If the majority of producers move overnight to distributing CPRM copy-controlled media, the hardware mass market has two choices: it can go with the flow, and give its customers the ability to play the latest music, read the latest news, view the latest movies... or it can ignore it. Ignoring it supposes that there's a sufficient number of non-compliant refuseniks out there to make it worth while.

Here's another, more dystopian way of looking at it. If CPRM-compliant hardware is the de facto standard in the marketplace, then media producers will be able to switch to disseminating only restrictive-copy content overnight, and they'll be able to do it as easily as flicking a switch. They will need the connivance of software applications, but it only takes a CPRM-compliant Internet Explorer to achieve this and the vast majority of desktop personal computers will have been assimilated. By this stage, you may well be living in a CPRM-free world, but the bets are that your neighbors won't be. Are you confident you'll be able to dissuade them, then?

10. IBM and Intel say that The Register's story mistakenly assumes that CPRM is intended for fixed hard disks, whereas it's only intended for removable media. Is this true?

Not if you examine the ATA extensions under consideration closely.

FACT: The CPRM ATA call interface requires information that standard ATA hard disks need, but that packet based removable ATAPI drives such as Zip and Jaz drives,don't: such as sector start and offset information. If the CPRM proposal under consideration by T.13 was for packet-based ATAPI drives, it wouldn't need this information.

FACT: We know of only one removable ATA drive: Castlewood's Orb. All others use ATAPI, or media-specific extensions on top of ATA (as with IBM's Microdrives) - that don't require extensions to the ATA command set.

From our conversations with the people behind the proposal, and public documents released by the T.13 committee, we'll agree that their focus to date has been on removable drives, and it's apparent that not all of the consequences of CPRM in fixed-drives have been discussed.

But unforeseen or not - and despite public protestations of their good intentions - the 4C Entity is delivering a solution tailor-made for fixed disk ATA drives, and building right into the specification for industry standard fixed drives. This is indisputable.

Now ask yourself, why is it there?

11. Won't an encrypted file system, or a virtual file system bypass CPRM?

Of course it will. In any operating system, device driver authors are free to reject the CPRM calls made by a software application. So the OS need not store CPRM digital media. Virtual file systems simply add another rejection point at which CRPM can be bounced off the system, and you're clean. With a software libre operating system (a BSD, Linux or AtheOS) let's assume that this is more likely to happen than with a commercial operating system (Windows, MacOS, Solaris).

But what then? We hear a GNU...

12. RMS says GNU/Linux and open source could fragment because of CPRM. How could this happen?

"If users accept the domination of centrally-controlled data, free software faces two dangers, each worse than the other: that users will reject GNU/Linux because it doesn't support the central control over access to these data, or that they will reject free versions of GNU/Linux for versions "enhanced" with proprietary software that support it. Either outcome will be a grave loss for our freedom."

In other words, "ideologically pure" systems could continue... but they'd be unable to read or view content provided by the media and entertainment industries. Some may redress this and include CPRM in their free software distributions, but in doing so, forever cede control of the content and information to the entertainment and media industries, argues Stallman.

13. CPRM ensures the artists and authors get paid. So isn't CPRM a fair way of doing this?

CPRM is sponsored by the distributors of entertainment media, not the people who create it, and we're yet to find an author or artist who approves of the mechanism. For the very simple reason, that an artists and authors' royalty is a tiny proportion of the fee charged by the distributor to the end user. The distributors gained powerful vertical monopolies when they were the gatekeepers of analog media, and tightly controlled both the mechanics of distribution, and the dissemination of information about authors and artists. The Internet destroys both these assumptions. So in by-passing the distributor, authors and artists stand to gain far more than they lose.

14. But publishers and record companies invest in promoting and nurturing new entertainers and authors. Aren't they entitled to a reward for this?

Of course they are. But is that reward proportionate to what the distributors invest? From a historical perspective - the timespan of human creativity - the control these distributors have exerted has been very brief, and very dependent on a specific technology.

But it would be a mistake to view the entertainment industry as a monolithic entity. The recording industry already views hit singles and CDs as loss leaders for merchandising....

15. I don't like CPRM. Who can I complain to?

You may complain to all of the parties mentioned above, who have public websites. We linked to them in this story. Intel's security group also has a form where you can post comments here.

When you've prevented CPRM from polluting the ATA specification used by hard drives, tell us, and we'll report it. ®